1. (Technical Field)
The present invention relates to a semiconductor module provided with electronic components, and in particular, to a semiconductor module provided with switching elements which serve as electronic components.
2. (Related Art)
There have been known power conversion apparatuses mounted in vehicles. Such apparatuses include apparatuses described by Japanese Patent Laid-open Publication Nos. 2000-333476 and 2008-136333.
The power conversion apparatus described in these publications has a configuration shown in FIG. 1. Practically, as shown, a power conversion apparatus 90 has a semiconductor module 900 including switching semiconductors 82 and a smoothing capacitor 94 electrically connected to both positive and negative sides of a DC power supply. This power conversion apparatus 90 is used to, for example, convert DC power of a DC power supply 91 to AC power.
Each of the switching semiconductors 92 has a switching element 95 which is for example an IGBT and a freewheel diode 96. Each switching element 95 has a gate terminal 95g connected to a not-shown control circuit board. This control circuit board controls on/off switching operations of the switching element 95. This control makes it possible to convert, to AC voltage, DC voltage applied between the positive-electrode terminal 98 of the high-potential side switching semiconductor 92H and the negative-electrode terminal 99 of the low-potential side switching semiconductor 92L, and to output the converted AC voltage from an AC output terminal 97.
However, the foregoing conventional semiconductor module 900 generates a surge voltage when each switching element 95 is switched on/off. Hence, to resist this surge voltage, each switching element 95 should have a high withstanding voltage. This results in a rise in manufacturing cost of the power conversion apparatus 90.
Meanwhile, there is known a technique of electrically parallel connecting a snubber capacitor to the switching element. This connection absorbs a surge generated by switching the switching element. However, a conventional semiconductor module has a snubber capacitor wire-bonded, so that the wire has a large amount of parasitic inductance L. This will cause a higher surge voltage (V=−L·di/dt). As a result, the effect given by the snubber capacitor is insufficient.